automatic to manual?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BayouBlazer88, Nov 1, 2002.

  1. BayouBlazer88

    BayouBlazer88 1/2 ton status

    Jul 31, 2002
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    Lafayette, LA
    I have an 88' K-5 Silverado with a 700R4 transmission and the recent post I read about going from auto to manual got me quite interested in doing the same. I don't know much about what types of transmissions are out there, but I know that if I switched to manual I would definitely need one with OD. What are my options for manuals and how much would a complete conversion cost if I did it myself using all new parts? (I'd be saving up for a while)
  2. imiceman44

    imiceman44 1 ton status Premium Member

    Aug 5, 2002
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    Sacramento, CA
    Well if you want to go with all new parts I guess you will be saving for a while.
    I think your options would be the NV4500 which is a 5 speed OD, it came on later mid 90's models.
    New I think it's $3500, but you can do search on that.
    It's a great tranny and every body wants one, or if you want the ultimate in strength, and have a big fat wallet, you can get the NV5600, If I recall right it was a 6 speed that came behind the Diesel Duramax.
  3. dyeager535

    dyeager535 1 ton status Premium Member

    Dec 13, 2000
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    Roy WA
    Be honest with yourself, do you REALLY need OD? Look at the NV4500 gear ratios. (there are actually two different sets of ratios, the ones most of us would want have the super low 1st) The super low 1st NV4500 has almost the exact same gear spacing as the SM465, with the addition of OD. (and IIRC, the OD isn't even as "deep" as the 700's, .070!)

    IMO, the hassle, (new holes in floor pan not in SM465/208 pre-dimpled/cut locations) cost (advance adapters pieces, cut driveshafts vs stock SM465 shafts), and gains (nothing but extra engine lug if stock gearing and anything short of 25" tires) of using the NV4500 are NOT worth it, unless you have insane gears to start with.

    I turn right around 2250RPM@60MPH (which is not taxing NOR lugging the engine) with the SM465, 33" tires, and 3.42 gears, and get 18mpg freeway. (on flat ground)

    I would say any RPM's less than about 2000 in my situation would lead me to have to downshift to second (third really) on the freeway (yuck!) if I wanted to pass, and anything over about 2500 is not necessary nor really desirable.

    My '83 had a 700R4, 3.08's, and 31", then 32" tires, and OD was about worthless. Even though I could get it into OD about 50MPH so long as the ground was perfectly flat, my best milege with OD was slightly worse than what I can get now without it. (17vs18 freeway, same in city, both in similar tune:worn out engines, one 305 now 350, but new plugs/wires/rotor, carbs rebuilt, etc)

    I guess my point is, the SM465 swap is easier, cheaper, and again, unless you need to run insane gears for wheeling with big tires, you'd be better off changing the rear axle ratio and tire size to compensate. I know mines MOSTLY on-road, but the 6.55:1 first makes a huge difference when I'm off road and need the gearing.

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